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Soil Compaction Effects
30 Questions
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Soil Compaction Effects

Created by
@TranquilQuadrilateral

Questions and Answers

What is an incorrect method to reach ZAV?

  • Encryption
  • Zero compaction (correct)
  • Decompression
  • Compression

    • What is a characteristic of ZAV access?

  • Requires zero compaction
  • Needs encryption
  • Involves compression
  • Cannot be reached (correct)

    • What is true about accessing ZAV?

  • It uses zero compaction
  • It requires a specific algorithm
  • It involves data encryption
  • It cannot be accessed (correct)

    • What is a limitation of ZAV?

    <p>It cannot be reached by zero compaction</p> Signup and view all the answers

    What is not a method to access ZAV?

    <p>Zero compaction</p> Signup and view all the answers

    What is false about ZAV?

    <p>It can be reached by zero compaction</p> Signup and view all the answers

    What is a restriction on accessing ZAV?

    <p>It cannot be accessed</p> Signup and view all the answers

    What is not possible with ZAV?

    <p>Accessing through zero compaction</p> Signup and view all the answers

    What is a limitation on ZAV accessibility?

    <p>It cannot be accessed</p> Signup and view all the answers

    What is not a characteristic of ZAV access?

    <p>Cannot be reached</p> Signup and view all the answers

    What happens to the air voids in a compacted soil sample when it reaches its maximum degree of compaction?

    <p>They are completely removed</p> Signup and view all the answers

    What is the significance of achieving a degree of compaction where all air voids are removed?

    <p>It results in a high dry density</p> Signup and view all the answers

    What would be the likely effect on the compaction curve if the soil sample is not fully compacted?

    <p>The dry density would be lower</p> Signup and view all the answers

    What is the primary cause of entrapped air in a soil sample during compaction?

    <p>Insufficient compactive effort</p> Signup and view all the answers

    Which of the following would NOT affect the compactive effort required to achieve a certain degree of compaction?

    <p>Atmospheric pressure</p> Signup and view all the answers

    What is the purpose of the Standard Proctor Equipment in soil compaction testing?

    <p>To compact the soil to its maximum density</p> Signup and view all the answers

    How does the presence of entrapped air affect the dry density of a compacted soil sample?

    <p>It decreases the dry density</p> Signup and view all the answers

    What happens to the compaction curve when the soil sample is over-compacted?

    <p>The dry density decreases</p> Signup and view all the answers

    What is the effect of increasing the compactive effort on the dry density of a compacted soil sample?

    <p>The dry density increases</p> Signup and view all the answers

    What is the significance of determining the maximum dry density of a soil sample?

    <p>It is an important property in geotechnical engineering</p> Signup and view all the answers

    How many times is the soil compacted for each lift in the Modified Proctor Test?

    <p>25 times</p> Signup and view all the answers

    What was the Modified Proctor Test developed during?

    <p>World War II</p> Signup and view all the answers

    What is the primary purpose of compacting a soil sample?

    <p>To remove all air voids</p> Signup and view all the answers

    What happens to the dry density of a compacted soil sample when it reaches its maximum degree of compaction?

    <p>It increases</p> Signup and view all the answers

    What is the effect of entrapped air on the dry density of a compacted soil sample?

    <p>It decreases the dry density</p> Signup and view all the answers

    What is the significance of the Standard Proctor Equipment in soil compaction testing?

    <p>To compact the soil and determine its maximum dry density</p> Signup and view all the answers

    What happens to the compaction curve when the soil sample is over-compacted?

    <p>It becomes flatter</p> Signup and view all the answers

    What is the effect of increasing the compactive effort on the dry density of a compacted soil sample?

    <p>It increases the dry density</p> Signup and view all the answers

    What is the primary cause of entrapped air in a soil sample during compaction?

    <p>Insufficient compactive effort</p> Signup and view all the answers

    Why is it important to remove all air voids from a compacted soil sample?

    <p>To achieve maximum dry density and stability</p> Signup and view all the answers

    Study Notes

    Compaction Process

    • The compaction process is assumed not to decrease the volume of solids or soil grains.

    Effects of Compaction

    • Increases shear strength, density, and bearing capacity of soil.
    • Allows for larger loads to be applied to compacted soils due to their increased strength.

    Mechanism of Compaction

    Cohesive Principles

    • Interaction between adsorbed layer and interpretable force.
    • Breaking up of old bonds and establishment of new bonds between particles.
    • Bending and distortion of soil particles.

    Cohesionless Principles

    • Rearrangement of soil grains.
    • Breaking up of some cementation.
    • Bending and distortion of soil particles.

    Theories of Compaction

    • Lambe theory: physico-chemical concept.
    • Proctor theory (1933): lubrication theory, where water addition causes a thin layer to be absorbed by soil grains, increasing the layer with more water.

    Role of Water in Compaction

    • Water lubricates soil grains (cohesionless soil), allowing them to slide easily and achieve a denser arrangement.
    • Water expansion of the double layer, leading to a more orderly arrangement of particles, resulting in higher density (clayey soil).

    Phase Diagram

    • For a given water content w, the maximum density (ZAV) cannot be reached by compaction.

    Soil Compaction

    • Objective: increase density, strength, bearing capacity, and reduce permeability and compressibility
    • Laboratory work: obtain maximum dry density and optimum water content
    • Field compaction: executed by contractors using rollers and compactors

    Compaction Process

    • Definition: increasing soil unit weight by reducing the soil void ratio using mechanical devices
    • Modified Proctor Test: compacting soil in five layers with a 10 Lbs hammer, 18 inches drop height, and 25 blows/layer
    • Modified Proctor Energy: 56,250 ft-lb/ft³, calculated by (25 blows/layer) * (5 layers) * (10 lbs) * (1.5 ft) / (1/30) ft³

    Comparison of Standard and Modified Proctor Tests

    • Mold size: 1/30 ft³ for both tests
    • Standard Proctor Test: 12" height of drop, 5.5 lb hammer, 3 layers, 25 blows/layer, and energy 12,375 ft-lb/ft³
    • Modified Proctor Test: 18" height of drop, 10 lb hammer, 5 layers, 25 blows/layer, and energy 56,250 ft-lb/ft³

    Compaction Procedure in Lab

    • Method: removing air voids to achieve a degree of compaction (S=1)
    • Water content: wW / vt vw

    Soil Compaction

    • Objective: Increase density, strength, bearing capacity, and reduce permeability and compressibility
    • Laboratory work: Obtain maximum dry density and optimum water content
    • Field Compaction: Contractors use rollers and compactors to achieve compaction

    Compaction Process

    • Definition: Increasing soil unit weight by reducing soil void ratio using mechanical devices
    • Reduces permeability and compressibility

    Modified Proctor Test

    • Similar to Standard Proctor Test with exceptions:
      • Soil compacted in five layers
      • Hammer weight: 10 lbs or 4.54 kg
      • Drop height: 18 inches or 45.72 cm
      • Calculated energy: 56,250 ft-lb/ft³

    Standard Proctor Test

    • Mold size: 1/30 ft³
    • Drop height: 12 inches
    • Hammer weight: 5.5 lbs
    • 3 layers
    • 25 blows/layer
    • Energy: 12,375 ft-lb/ft³

    Compaction Procedure in Lab

    • Method: Drop hammer 25 times onto confined soil
    • Soil divided into three lifts, each compacted 25 times
    • Done 4-6 times from dry to wet
    • Goal: Achieve maximum dry density and optimum water content

    History of Modified Proctor Test

    • Developed during World War II
    • By the U.S.

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    Description

    This quiz covers the effects of soil compaction, including increased shear strength, density, and bearing capacity. It explores how compaction enables larger loads to be applied to soils.

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